How do you get better at "treating yourself?"

I don't know if it is a product of super deep-rooted low-self esteem (such that it doesn't manifest as blatant thoughts but rather through sentiments when I do certain things), or because my parents raised me to be super frugal as they always complained about expenses and wastes of money, but I have trouble really treating myself.

Not to be boastful, but I make quite good money right now. Let's just say I'm currently in a position where I have $6k+ excess cash a month that I just put directly into my investment accounts and HYSA. And I've been doing that for 2 years, so financially I'm quite in a good spot. But I'm terrible at treating myself.

I haven't taken a "proper" vacation like travelling in any way these years. Solo travel feels scary and I'm scared I won't like it that much and it'll be a waste of money. I don't buy snacks like chips or buy coffee outside because I keep thinking to myself "that's such a waste of money, I won't get $6 of enjoyment out of that!" I feel unwilling to buy like things I consider too expensive even if they're cheap. Like most of my meals I make for myself are just chicken breast/thigh/ground beef as a protein because salmon/shrimp feel too expensive, and $15+ for any meal feels crazy. I also never order food out because I feel bad spending like $25 on delivery for a single lunch. I haven't bought any clothing in the past 2 years besides a new pair of shoes (because I'm a person who legit just has one pair of everyday shoes that I replace every 2 years) because I have perfectly good clothing and it feels wasteful both money and environmentally to dispose of it.

I know this isn't simply a "you're being cheap!" thing because I have no problem spending money on other people. I recently paid for my parents' vacation to their home country. I'm always happy to treat my friends who are unemployed/make less than me to meals because I want them to just have fun and I enjoy their company. It's just when it comes to money on myself I feel overly stingy.

I feel this is hindering some aspects of my life (outdated fashion, not eating the food/drink I want unless I have company, not going out often). It's like I can finally afford things but I hate spending money if it's on myself. Like I'll be envious of people who have cool things or are doing cool things and I'm like, yeah I can afford it and do it too but the money sink will make me feel like shit.

I'm aware this is a super privileged problem to have and some people will be like "wish I had this guy's problem!" But it's like, since going from making very little to my current income, my expenditure and financial mindset has not changed.